using System;
using System.Collections;

using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.X509
{
	/**
	 * The extendedKeyUsage object.
	 * <pre>
	 *      extendedKeyUsage ::= Sequence SIZE (1..MAX) OF KeyPurposeId
	 * </pre>
	 */
	public class ExtendedKeyUsage
		: Asn1Encodable
	{
		internal readonly IDictionary usageTable = Platform.CreateHashtable();
		internal readonly Asn1Sequence seq;

		public static ExtendedKeyUsage GetInstance(
			Asn1TaggedObject	obj,
			bool				explicitly)
		{
			return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
		}

		public static ExtendedKeyUsage GetInstance(
			object obj)
		{
			if (obj is ExtendedKeyUsage)
			{
				return (ExtendedKeyUsage) obj;
			}

			if (obj is Asn1Sequence)
			{
				return new ExtendedKeyUsage((Asn1Sequence) obj);
			}

			if (obj is X509Extension)
			{
				return GetInstance(X509Extension.ConvertValueToObject((X509Extension) obj));
			}

			throw new ArgumentException("Invalid ExtendedKeyUsage: " + obj.GetType().Name);
		}

		private ExtendedKeyUsage(
			Asn1Sequence seq)
		{
			this.seq = seq;

			foreach (object o in seq)
			{
				if (!(o is DerObjectIdentifier))
					throw new ArgumentException("Only DerObjectIdentifier instances allowed in ExtendedKeyUsage.");

				this.usageTable.Add(o, o);
			}
		}

		public ExtendedKeyUsage(
			params KeyPurposeID[] usages)
		{
			this.seq = new DerSequence(usages);

			foreach (KeyPurposeID usage in usages)
			{
				this.usageTable.Add(usage, usage);
			}
		}

#if !SILVERLIGHT
		[Obsolete]
		public ExtendedKeyUsage(
			ArrayList usages)
			: this((IEnumerable)usages)
		{
		}
#endif

		public ExtendedKeyUsage(
			IEnumerable usages)
		{
			Asn1EncodableVector v = new Asn1EncodableVector();

			foreach (Asn1Object o in usages)
			{
				v.Add(o);

				this.usageTable.Add(o, o);
			}

			this.seq = new DerSequence(v);
		}

		public bool HasKeyPurposeId(
			KeyPurposeID keyPurposeId)
		{
			return usageTable[keyPurposeId] != null;
		}

#if !SILVERLIGHT
		[Obsolete("Use 'GetAllUsages'")]
		public ArrayList GetUsages()
		{
			return new ArrayList(usageTable.Values);
		}
#endif

		/**
		 * Returns all extended key usages.
		 * The returned ArrayList contains DerObjectIdentifier instances.
		 * @return An ArrayList with all key purposes.
		 */
		public IList GetAllUsages()
		{
			return Platform.CreateArrayList(usageTable.Values);
		}

		public int Count
		{
			get { return usageTable.Count; }
		}

		public override Asn1Object ToAsn1Object()
		{
			return seq;
		}
	}
}
